Hoisting crane

ABSTRACT

A hoisting crane of the type having a horizontal jib which is pivotally mounted on a vertical tower and supports thereon a movable carriage having a lifting means. The jib is formed of a plurality of detachably couplable modules each of which is formed of at least one upper and at least one lower member extending parallel to each other in the direction of the longitudinal axis of the jib. The longitudinal members of the respective modules all have the same spacing relative to each other so that all of the modules may be constructed with the same overall dimensions on a common jig. The modules which form a jib may have varying strengths to permit the modules which are closer to the pivotal mount on the tower to have a greater load-carrying capacity than those which are disposed toward the free end of the jib, and this is accomplished by having the associated members of some of the modules formed with a greater material cross-section than that of the corresponding members of other of the modules.

United States Patent 11 1 3,706,285 Gynt et al. 1 Dec. 19, 1972 i 1HOISTING CRANE Primary Examiner-James B. Marbert Assistant Examiner-D.W. Keen {72] inventors: Lars Gynt; Lennart l-lolm, both of vasteras,Sweden Attorney-Sommers 8; Young [73] Assignee: Linden-Alimok AB,Vasteras, [57] ABSTRACT Sweden A hoisting crane of the type having ahorizontal jib [22] Filed: Jan. 18, 1971 which is pivotally mounted on avertical tower and supports thereon a movable carriage having a lifting[2]] Appl' l07076 means. The jib is formed of a plurality of detachablycouplable modules each of which is formed of at least [30] ForeignApplication Priority Data one upper and at least one lower memberextending parallel to each other in the direction of the longitu- Jan.27, 1970 Sweden ..978/70 dinal axis of the j The longitudinal members ofthe respective modules all have the same spacing relative 2? 212/144 toeach other so that all of the modules may be con I! i e "B666 Structedthe same overall dimensions on a Fle d of Search ..l04/124, 14/3, 4, 7,13, 14, mo jig The modules which form ajib may have vary 212/46 144 ingstrengths to permit the modules which are closer to the pivotal mount onthe tower to have a greater {56] References cued load-carrying capacitythan those which are disposed UNITED STATES PATENTS toward the free endof the jib, and this is accomplished by having the associated members ofsome of 3. 1104 5/1969 Grider "212/144 the modules formed with a greatermaterial cross-sec- 3l433l459 3/1969 Logan Min/144 tion than that of thecorresponding members of other 2,575,564 11/1951 Rinkel r ..212/l44 fthe 2,335.522 11/1943 Letourneau t ..212/144 6 Claims, 4 Drawing Figures7 :4 izagnii iii memmucmm 3.766.285

SHEEI 1 BF 2 LARS GYNT LEN NART HOLM PATENTEDIJENQ I912 3.706.285

SHEET 3 UF 2 LARS GYNT LENNART HOLM I-lOlSTlNG CRANE This inventionrelates to a hoisting crane adapted particularly for building purposes,comprising a freely projecting jib, which is mounted, for example, on atower or a derrick and along which can be moved a carriage with alifting means, which jib has a lattice structure and comprises at leastone upper and at least one lower longitudinal frame rod.

A hoisting crane for building purposes usually comprises a towercarrying at its top end portion a horizontal jib. The jib in its turnsupports a carriage with a lifting tackle or lifting cables suspendedthereon. A carriage of this type being movable along the entire jib, thecrane can cover a rectangular working range in a vertical plane.

With increasing demands of the building industry for more rationalbuilding methods, the working ranges of the building cranes and,thereby, the length of the jibs have increased. With increasinghorizontal operation range for a hoisting crane, the lifting capacitybecomes increasingly dependent on the dead weight of the jib. Forproducing jibs with a low dead weight, the jibs are given a latticestructure, which in many cases is made of a high-grade structural steel.

In conventional cranes, a jib is supported by one or more stay membersanchored at the outer half of the jib. The other end of such a staymember usually extends beyond a breaking point located higher than thejib in the extension of the crane tower. A second mounting for such ajib is provided at the connection to the crane tower.

.libs usually have a rectangular or triangular crosssection, with aframe rod placed at each joint of the cross-section. The lower and upperframe rods are connected together by vertical rods and diagonal rods. In

known building cranes, often one and the same frame rod or diagonal rodis subjected either to compressive forces or tensile forces, dependingon whether the carriage with load is outside or inside of the point inwhich the carrying stay member of the jib is anchored at the jib.

For reasons already mentioned, it is desired to utilize all of thematerial in the jib at optimum for the strength of the jib. in knownjibs, however, a substantial increase in weight cannot be avoided,because the main part of the lattice rods is to be dimensioned such asto be able to transfer compressive forces and is calculated with respectto the risk of breaking. Lattice rods in a jib of known design,moreover, when the crane is in operation, are subjected also toalternating loads by both tensile and compressive forces, which atstraining crane operations can cause breaks due to fatigue of the rodmaterial. A number of such cases are known.

Building cranes often have jibs with a length of 30-40 m. It is therebyof decisive importance to place the center of gravity of the job nearthe slewing center, because hereby not only the dead weight moment inthe vertical direction, but also the effect of horizontally actingbending moments is reduced which are caused by forces of inertia on thejib at the start and braking of its slewing motion.

The importance of a smaller slewing radius for the gravity point of ajib is easily understood when com sidering that all parts of a jibduring the start and braking of its slewing motion are subjected toforces of inertia, the magnitude of which is directly proportional tothe product of the dead weight of the part and of the distance to thecenter for the slewing motion.

In the jib described below. the center of gravity is placed closer tothe slewing center than is possible with jibs of known design. Due tothe construction of the jib, furthermore, the total surface exposed towind load is smaller than in known building cranes. This involves,besides, advantages from a dimensioning point of view and improves theoperating properties.

The jib, furthermore, is so designed that it comprises a substantiallyreduced number of rods subjected to compressive forces. Every rodcomprised in a jib according to the invention is subjected to only onetype of load, either tension or compression, which implies aconsiderable reduction of the breaking risk resulting from fatigue ofthe material.

Tower cranes for building purposes are produced in series. It isconventional for the tower to be assembled of construction modules.Heretofore, it has not been possible to manufacture jibs in acorresponding way with modules, due to the reason that, in conventionaljibs the loads on a jib, module located at the outer portion of a jibare different from those on a jib module located far inwardly on a jib.

One characterizing feature of the jib according to the invention is thatit is supported entirely without outside stay members.

From a production technical point of view, the invention renderspossible good flexibility and adaptation to the market.

At a building site, it is often desired to extend the jib of anavailable building crane. in conventional building cranes, such anextension can be made only in exceptional cases, because the load in thecross-section subjected to the greatest load, which load applies to themounting of the carrying stay member, increases with the relationbetween the length of the jib outside of the stay member after theextension and the length of the jib outside the stay member prior to theextension.

In the jib according to the invention, the cross-section subjected tothe greatest load always is located at the mounting on the crane tower.Accordingly, the load in the cross-section only increases with therelation between the length of the entire jib after the extension andthe length of the entire jib prior to the extension.

This implies for a normal jib extension that the load in the dimensionedcross-section of a jib of known design increases by about 40 while thecorresponding load increase for the jib according to the invention onlyis about 10 From a safety point of view, the invention further involvesthe advantage that the load moment switch, which must be found at allcranes of this kind, must not be reset after a change of the jib length.Consequently, no new inspection is required either.

The jib in its entirety being dimensioned so as to carry vertical loadswithout additional stay members, and this implies as a furtherachievement that the horizontal rigidity is improved substantially overthat of known jibs.

Furthermore, the mounting time required for a building crane accordingto the invention is reduced considerably compared with known buildingcranes as no stay cables and top supports have to be mounted.

The aforesaid disadvantages are eliminated and the aforesaid advantagesare obtained by the hoisting crane according to the invention, which ischaracterized in that the jib has no outside stay members and in itslongitudinal direction is divided into a number of construction moduleshaving different bearing capacity such that the bearing capacityincreases from the free end of the jib inwardly, and that the differentbearing capacities are obtained by different cross-sectional dimensionsof at least one of the rods comprised in the modules.

An embodiment of the crane according to the invention is described belowwith reference to the accompanying drawing, in which FIG. 1 is a lateralview of a building crane with a jib assembled of construction modules,and

FIGS. 2, 3 and 4 are a lateral view, anend view and a view seen fromabove, respectively, of a construction module of which an entire jib canbe assembled.

The building crane comprises a derrick 2 secured on a foundation 3, aslew base plate 4, a jib 5, which in this embodiment is assembled offive construction modules, a counterweight 6, hoisting machinery 7, aslewing machinery 8, a carriage 9, lifting hook 10, lifting cable 11,and carriage machinery 20.

A construction module comprises upper frame rods 12 and lower frame rods13, connected together by rods 14 and 15 arranged perpendicularly tosaid frame rods and by diagonal rods 16 and 17. The frame rods 12 and 13as well as the rods 14, 15, 16 and 17 may be rolled sections or hollowbodies. In FIG. 3, the upper and lower frame rods 12 and 13,respectively, are shown to be square tubes, which may have square orrectangular cross-section. One characterizing feature of a constructionmodule is that all diagonal rods in a lateral projection (FIG. 2) havethe same direction.

The drawing shows a construction module having rectangular crosssection. The invention, however, allows also for applying constructionmodules with another cross-section, for example of triangular shapehaving a point turned upwardly or downwardly. One prerequisitecondition, however, is that all diagonals in a lateral projection of theconstruction module have the same direction.

The upper frame rods 12 are provided with flanges 18 for connectingtogether the construction modules by bolts. The lower frame rods 13 areprovided with guide means comprising guide pins 19 for effectingcentering within a frame rod of an adjacent construction module.

The mounting method for a jib according to the invention is simpler thanthat for conventional jibs because the lower frame rods only transfercompressive forces, so that connections in their usual meaning are notrequired. What is required is merely a means 19 for centering. Thisoffers the further advantage that the lower frame rods on their outsideare entirely smooth and thereby can serve as a runway for the carriage9.

All construction modules for a jib have the same outer dimension, whichis a prerequisite condition for production in series. It is therebypossible to utilize the same production line, the same welding fixturesand other equipment for all jib modules.

All construction modules are so manufactured and iiiiific' iiil'fhifiillit'is iiil'iifiiirlf' fi ciiiifi. tion module, all rods comprisetubes or other hollow bodies, in which case different bearing capacityis obtained in that the outside or inside dimension for all rods of acertain kind is equal while the bearing capacity for differentconstruction modules can be varied by choosing a varying materialthickness for the rods.

What we claim is:

I. In a hoisting crane of the type comprising a horizontal jib pivotallymounted on a vertical tower and supporting thereon a movable carriagehaving a lifting means, the improvement which comprises:

said jib being formed of a plurality of detachably couplable moduleseach of which comprises at least one upper and at least one lower memberwhich members extend parallel to each other in the direction of thelongitudinal axis of the horizontal jib,

said members in each of the respective modules of the jib all having thesame spacing relative to each other so as to permit each jib-formingmodule to be constructed with the same dimensions in a common jib,

some of said jib-forming modules having their as sociated members formedwith a greater material cross-section than that of the correspondingmembers of other of said modules so as to permit an increase in theload-carrying strength of the modules in a direction from the free endof the jib toward its pivotal mounting on said tower without varying theoverall cross-sectional dimensions of the several modules forming acomplete jib.

2. The crane of claim 1, in which said upper and lower longitudinalmembers of each module are connected together by substantially verticalrods and diagonal rods, all of said diagonal rods extending insubstantially the same direction and sloping downwardly toward the freeend of the jib so as to be in tension under load.

3. The crane of claim 1, in which each module is formed of hollow tubesand corresponding tubes of the respectively difi'erent modules havingdifferent loadbearing capacity have the same outer dimension.

4. The crane of claim 1, in which each module is formed of hollow tubesand corresponding tubes of the respectively different modules havingdifferent loadbearing capacity have the same inner dimension.

5. The crane of claim 1, which further includes a detachable couplingmeans to couple adjoining ends of said modules, each said coupling meanscomprising coupling elements at the respective ends of the upperlongitudinal members for providing a tension coupling therebetween andcoupling elements for the respective ends of the lower longitudinalmembers which provide longitudinal alignment of the corresponding lowermembers.

6. A crane according to claim 1, characterized by a smooth transitionbetween the lower members of the modules so that said rods can serve asa runway for the carriage.

t l i i

1. In a hoisting crane of the type comprising a horizontal jib pivotallymounted on a vertical tower aNd supporting thereon a movable carriagehaving a lifting means, the improvement which comprises: said jib beingformed of a plurality of detachably couplable modules each of whichcomprises at least one upper and at least one lower member which membersextend parallel to each other in the direction of the longitudinal axisof the horizontal jib, said members in each of the respective modules ofthe jib all having the same spacing relative to each other so as topermit each jib-forming module to be constructed with the samedimensions in a common jib, some of said jib-forming modules havingtheir associated members formed with a greater material cross-sectionthan that of the corresponding members of other of said modules so as topermit an increase in the load-carrying strength of the modules in adirection from the free end of the jib toward its pivotal mounting onsaid tower without varying the overall crosssectional dimensions of theseveral modules forming a complete jib.
 2. The crane of claim 1, inwhich said upper and lower longitudinal members of each module areconnected together by substantially vertical rods and diagonal rods, allof said diagonal rods extending in substantially the same direction andsloping downwardly toward the free end of the jib so as to be in tensionunder load.
 3. The crane of claim 1, in which each module is formed ofhollow tubes and corresponding tubes of the respectively differentmodules having different load-bearing capacity have the same outerdimension.
 4. The crane of claim 1, in which each module is formed ofhollow tubes and corresponding tubes of the respectively differentmodules having different load-bearing capacity have the same innerdimension.
 5. The crane of claim 1, which further includes a detachablecoupling means to couple adjoining ends of said modules, each saidcoupling means comprising coupling elements at the respective ends ofthe upper longitudinal members for providing a tension couplingtherebetween and coupling elements for the respective ends of the lowerlongitudinal members which provide longitudinal alignment of thecorresponding lower members.
 6. A crane according to claim 1,characterized by a smooth transition between the lower members of themodules so that said rods can serve as a runway for the carriage.